Document and Entity Information
9 Months Ended
Sep. 30, 2017
Document and Entity Information  
Entity Registrant Name MAGELLAN HEALTH INC
Entity Central Index Key 0000019411
Document Type 10-Q
Document Period End Date Sep. 30, 2017
Amendment Flag false
Current Fiscal Year End Date --12-31
Entity Current Reporting Status Yes
Entity Filer Category Large Accelerated Filer
Entity Common Stock, Shares Outstanding 24,042,290
Document Fiscal Year Focus 2017
Document Fiscal Period Focus Q3